Fix crash when not setting GCOV_PREFIX.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130834 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/runtime/libprofile/GCDAProfiling.c b/runtime/libprofile/GCDAProfiling.c
index 2dcf22d..13fe0fd 100644
--- a/runtime/libprofile/GCDAProfiling.c
+++ b/runtime/libprofile/GCDAProfiling.c
@@ -54,7 +54,7 @@
   prefix = getenv("GCOV_PREFIX");
 
   if (!prefix)
-    return strdup(filename);
+    return strdup(orig_filename);
 
   filename = malloc(strlen(prefix) + 1 + strlen(orig_filename) + 1);
   strcpy(filename, prefix);